UserControl for Counting text of given textbox

TextCounter.cs

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Drawing;
using System.Data;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using System.IO;

namespace TextCounter
{
    public enum DisplayFormat { Remaining = 0, Typed = 1, Both = 2, MaxLength = 3 }

    public partial class TextCounter: UserControl
    {
        [Browsable(true), Description("Output Image Format"), Category("Misc")]
        public DisplayFormat ShowCountAs { get; set; }

        [Description("TextBox Name"), Category("Misc")]
        public string TextBox_Name { get; set; }

        private TextBox sourceTextBox;
        public TextCounter()
        {
            InitializeComponent();
            
            _ = TaskUpdateFromParent();

        }

        private async Task TaskUpdateFromParent()
        {
            await Task.Delay(600);

            if (TextBox_Name == null) TextBox_Name = "tboxSource";
            
            if (this.Parent == null || this.Parent.Controls.Count < 1) return;

            // define TextBox_Slug
            if (this.Parent.Controls[TextBox_Name] != null)
            {
                sourceTextBox = (TextBox)this.Parent.Controls[TextBox_Name];

                sourceTextBox.KeyUp -= OnTextBox_KeyUp;
                sourceTextBox.KeyUp += OnTextBox_KeyUp;

                sourceTextBox.TextChanged -= OnTextBox_TextChanged;
                sourceTextBox.TextChanged += OnTextBox_TextChanged;

                upateLabel();
                this.BackColor = Control.DefaultBackColor;
                this.ForeColor = Control.DefaultForeColor;
                //lblCount.ForeColor = this.ForeColor;

            }

        }

        private void OnTextBox_TextChanged(object sender, EventArgs e)
        {
            upateLabel();
        }

        private void OnTextBox_KeyUp(object sender, KeyEventArgs e)
        {
            upateLabel();
        }

        private void upateLabel() {
            {
                if (ShowCountAs == DisplayFormat.Remaining)
                    lblCount.Text = (sourceTextBox.MaxLength - sourceTextBox.Text.Length).ToString();
                else if (ShowCountAs == DisplayFormat.Typed)
                    lblCount.Text = (sourceTextBox.Text.Length).ToString();
                else if (ShowCountAs == DisplayFormat.MaxLength)
                    lblCount.Text = sourceTextBox.MaxLength.ToString();
                else
                    lblCount.Text = (sourceTextBox.MaxLength - sourceTextBox.Text.Length).ToString() + "/" + sourceTextBox.MaxLength.ToString();
            }

            lblCount.BackColor = getColor();

        }


        private Color getColor() {

            int max = sourceTextBox.MaxLength;
            int current = sourceTextBox.Text.Length;
            
            int filledPercentage = (current * 100 ) / max;

            /*
            Console.WriteLine(" current : " + current);
            Console.WriteLine(" max : " + max);
            Console.WriteLine(" filledPercentage : " + filledPercentage);
            */

            if (filledPercentage <= 50)
                return Color.FromArgb(255, 0, 240, 0);
            if (filledPercentage > 50 && filledPercentage <= 85)
                return Color.FromArgb(255, 150, 250, 0);
            if (filledPercentage > 85 && filledPercentage < 100)
                return Color.FromArgb(255, 255, 210, 0);
            else
                return Color.FromArgb(255, 255, 100, 100);

        }

    }
}